Combustion chambers of a combustion system, for example of a gas turbine, are customarily equipped with a heat shield which protects a subjacent support structure against a direct contact with a hot gas flow. Depending upon position in the combustion chamber, or with regard to the hot gas flow, the heat shield, or individual segments of it, in this case is or are exposed to a variable temperature stress.
A nozzle segment for use in a gas turbine is known from EP 1 143 109 B1 and comprises a side wall, which extends essentially radially between a nozzle wall and a cover, and has an inwardly turned flange which is at a distance from the nozzle wall. The inwardly turned flange together with the nozzle wall and the side wall defines an undercut section, wherein a plurality of openings which lead through the inwardly turned flange are provided to allow cooling medium to flow into the undercut section for impingement cooling of the side wall. As a result of this, an essentially even cooling of the heat shield, or of the side wall, is achieved. The heat shield, depending upon position in the combustion chamber, is exposed to a temperature stress of variable degree, which for optimum cooling necessitates locally variable cooling.